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Clay Pot Irrigation : the latest and greatest in garden hardware

With the persistence of the dry weather I thought I'd share with you the latest version of my clay pot irrigation system. I've been experimenting with the setup for a few years and this rig works to my satisfaction and prevails against, weather, pet dogs,bush turkeys,  cane toads and crows.

THE POT

Get yourself a un-glazed terracotta clay pot at least 20 cm in diameter. That should cost you no more than $4.

THE HOLE

Fill in the hole at the bottom of the pot so that it doesn't leak. I prefer to cover the pot base with a layer of grout.

THE SHADE CLOTH

Any sections of shade cloth will do. You may have pieces laying around the shed. I find successive layering is the best approach because the layers sharply reduce evaporation but still allow the diffusion of water when you direct the hose at the pot opening. Three layers of shade cloth seems to be the optimum number for efficacy.  Trust me: you want the top layer to be really bright so see if you can beg some red 'safety' cloth from a building site. Most construction sites dispose of the cloth when they are finished building.

THE PEGS

Either buy some pegs made for pinning weed mat, or make your own by cutting and bending wire.Stretch the cloth firmly so that you get a sort of tight drum effect.

You want to anchor the covers securely because family dogs, possums, birds and the like may stand on them and force them to depress. When they curve down cane toads occupy the space to rejuvenate their skin.

POSITIONING THE POTS

Generally depending on your soil you should be able to bury your pots 1-1.5 metres apart.You may need to experiment given your conditions and what you grow but  a wetting zone  of 60 cm is a useful rule of thumb.

THE PROTOCOL

You'll find that with a concentrated hose spray you can fill several pots from the one standing position.How often you'll need to do that will depend on your soil. The system is primarily driven by gravity so it is best to keep the pots 'topped up' and never allow them to empty. You'll be able to observe the water rise to the brim -- you can even hear it as it sounds like filling a kettle at a tap.

In my sandy soil I attend my pots every second day.

MOUNDING

I designed my garden around mounds, roughly 1.5 metres in diameter then buried pots at the apex like a crater in a volcano. This elevated area makes a useful contour that mirrors the presumed reach of moisture  which diffuses in a tea drop or pear shape pattern from the clay pot reservoir.

A NETWORK OF SPRINGS

You could move your pots around to suit your planting schedule, but I find it best to treat them like underground springs  that consolidate & water the immediate ecology over time. So mine are permanent fixtures in the landscape.

ROOTS

The closer seedlings are planted to the pots, the more consistent will be their water uptake. Close planting of many plants seems to work well under these conditions. However, any time you plant seedlings in the wetting zone, you need to water them directly until their roots grow out and orientate to the irrigation resource.

ADVANTAGES OF CLAY POT IRRIGATION

  1. Clay Pots are cheap.
  2. The system is adaptable to your needs and can be added to as required.
  3. Buried clay pots can be deployed regardless of your garden slope and contour.
  4. Clay Pot irrigation is extremely water efficient.Because each pot has a set volume you can easily judge how much water you are using to irrigate.Water is delivered as needed  directly to the soil where plants are rooted.
  5. Little water is lost from the soil or lost from runoff or evaporation into the air – as happens with sprinklers. There is also no water loss into the soil below the root horizon. The soil is never under or over saturated because the optimum soil water level for plant growth is controlled by demand from the soil and plant roots.
  6. Clay Pot irrigation is 70-90% more efficient than flood or sprinkler irrigation and may even be more efficient than modern low-pressure drip systems.
  7. Clay Pots irrigate under the mulch so there is less opportunity for weeds to grow or fungal diseases to take hold of plants.
  8. With the wide brim of the 20cm pot, filling is much easier than other olla systems with their cumbersome narrow lips. The shade cloths solve any evaporation problems.
  9. Although you need to fill the pots manually, you can vary the frequency and the number you attend to according to weather and garden conditions.
  10. Maintenance is almost zero. If you maintain regular top ups, you'll find that all that is required is to now and then clear mulch or fallen leaves off the pot covers.
  11. Clay Pots attract garden worms big time. Once established worms will treat the clay pot wet zone as a community neighborhood and move in to stay. Remove a clay pot and the earth sides of the hole will be like a worm tenement house.
  12. The shade cloth covers not only reduce evaporation and keep cane toads away from  the water below but the thick mesh layers resists mosquito invasion.

DISADVANTAGES OF CLAY POT IRRIGATION

  1. You have to fill the pots regularly.
  2. Filling clay pots with water takes time: 15-20 seconds per pot!
  3. Your targeted growth medium is shallow as that's the wetted part. This is why you need to mulch the soil to protect it.
  4. Not all un-glazed clay pots you can buy are porous. Different firings, clay sources and grog mixes can effect porosity.  So be prepared to reject the occasional pot for irrigation use -- even if they seem part of the same batch as those that are permeable.

FERTILITY HOLE

I should add that the option for perennials is the fertility hole.

  • dig a trench slightly deeper  than the depth of your clay pots.
  • instead of inserting a pot, place upright rolled up newspaper (such as local community rags you get on your nature strip) in the hole and throw in some coir and manure. You can also add dry or rotting sticks, even kitchen scraps.
  • cover the space with a circle of cut (preferably red) shade cloth and weigh it down with a small log or rock.
  • when hosing treat the marked hole as a pot and hose it deeply so that it fills and engorges.

The hole acts as a sponge -- holding moisture, compost and fertilizer which will rot down over time.  You can dig these holes when you plant out anew or even add them at a later date. They work as a companion to perennials and act as a moisture reservoir -- similar to  the pots..

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Comment by Dave Riley on October 3, 2017 at 8:59

Here's a schematized sketch of the system I'm pursuing.

No shown are various ground covers I experiment with. these I simply cut back or move aside and plant ion the vacancy.

Over time the mounds tend to merge with one another into the one undulating bed as the contour softens.

Comment by Andrew Cumberland on September 30, 2017 at 20:47

Nice article mate.  Thanks for sharing. 

Comment by Dave Riley on September 28, 2017 at 11:25

I should add that the option for perennials is the fertility hole.

  • dig a trench slightly deeper  than the depth of your clay pots.
  • instead of inserting a pot, place upright rolled up newspaper (such as local community rags you get on your nature strip) in the hole and throw in some coir and manure. You can also add dry or rotting sticks, even kitchen scraps.
  • cover the space with a circle of cut (preferably red) shade cloth and weigh it down with a small log or rock.
  • when hosing treat the marked hole as a pot and hose it deeply so that it fills and engorges.

The hole acts as a sponge -- holding moisture, compost and fertilizer which will rot down over time.  You can dig these holes when you plant out anew or even add them at a later date. They work as a companion to perennials and act as a moisture reservoir -- just like the pots..

Comment by Elaine de Saxe on September 28, 2017 at 9:19

Good update, Dave.

Comment by Mary-Ann Baker on September 28, 2017 at 7:02

thanks Dave another incredible source of information and food for thought. experimenting and researching ways to adapt to our garden design ( or lack thereof) 

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